Glued laminated wood and method of manufacturing the same

ABSTRACT

Glued laminated wood which has a novel laminated structure and may be fabricated from small-sized veneer sheets, and method of manufacturing such laminated wood are provided. The glued laminated wood in its continuous form is made from a series of unit-length veneer sheets each having the same length and thickness which are laminated in a laid-up arrangement in which each of the veneer sheets is lapped on another and offset therefrom in the direction of its length at a regular interval determined by the number of plies to be in the laminated wood product and the length of the unit veneer sheets. It has a novel structure in that each veneer sheet therein has tandemly spaced straight length portions which are parallel to each other, but successively displaced from each other in the direction of the thickness of the product, there being a somewhat S-shaped curved length portion of the veneer sheet between any successive pair of these straight length portions. The number of such straight length portions in each unit veneer sheet is equal to the number of plies in the product being made, and the length of each such straight length portion is nominally determined by dividing the length of the unit veneer sheet by the number of plies.

FIELD OF THE INVENTION

The present invention relates generally to glued laminated wood,including plywood and to a method of manufacturing the same. Morespecifically, it relates to glued laminated wood plywood having a novellaminated structure of veneers and to a method of manufacturing thesame.

BACKGROUND OF THE INVENTION

In the so-called improved woods, several types of sheet or boardmaterials are available, among which glued laminated wood, includingplywood is one of the most popular wood sheet materials.

In general, glued laminated wood which is composed of plural layers ofveneers laminated or glued together into a sheet form achieves itsthickness from the thicknesses of the individual component veneers andthe number of layers of such component veneers. Such glued laminatedwood, including plywood, as compared with sawn lumber, exhibits improveduniformity in strength and provides a useful wood sheet material whichcan be made in much larger areas. Therefore, such glued laminated wood,including plywood comes in a great variety of sizes and thicknesses, andcan be laminated in different ways to meet varying requirements of themarket. It is therefore used for a wide range of applications including,construction, housing, furniture, etc.

Under present circumstances of limited supply and therefore increasingprices of logs, it is an urgent task of every manufacturer to establisha manufacturing system which can permit production of various kinds ofglued laminated wood sheets or panels having different lengths, widthsand thicknesses with the highest possible yield rate and the minimumcost in production, labor and materials, in order to fulfill theabove-said versatile demands of the market. In addition, it is apotential task of the producer to develop new fields of application forsuch glued laminated wood through further improvements of its inherentadvantages.

It is evident that the above-mentioned urgent problems cannot be solvedby glued laminated wood having conventional structure which inevitablycalls for and requires selection of component veneers whose sizes aredetermined by the sizes of the laminated wood sheets or panels to bemade. For example, it is presently necessary to cut veneer sheets from alog which is eight feet long in order to make a typical 4'×8' plywoodpanel, for reasons understood by those familiar with the manufacture ofplywood. This requirement makes conventional plywood panels more costly.It is therefore believed that an effective approach to the problem wouldbe to establish a technology by which various sizes of glued laminatedwood, including plywood may be fabricated from veneers of a reducednumber of sizes or, most preferably, from veneers of only one size.Moreover, it would be a significant advance if glued laminated woodpanels could be manufactured from veneers which are smaller than theintended panel size. In other words, the present invention is intendedto provide more effective utilization of veneers. This is because, inthe manufacture of glued laminated wood plywood, the process involved inmaking veneers from logs is more problematic and calls for more laborthan does the process of making the laminated wood from the veneers.Thus, improvements in the former process can make a greater contributionto the reduction of costs and to the simplification of laminated woodmanufacturing as a whole. However, when realizing a technology whichcould make possible production of various glued laminated wood sizesfrom veneers of a reduced number of veneer sizes or of a single size, itwould be important to prevent the introduction of any new defects in theproducts which would be made in that way. The glued laminated wood andthe method for its manufacture according to the present invention weredeveloped with these considerations in mind.

Published Japnese Patent Application No. 104006 (1976) shows gluedlaminated wood composed of a series of short veneers which are allparallel-laminated in such an arrangement that each veneer is offset orshifted with respect to its adjacent veneer at a regular interval oflength, and the ends of all of the veneers are exposed on both faces ofthe sheet. However, the glued laminated wood product of the presentinvention is different, and is produced in a different way.

It is an object of the present invention to provide glued laminated woodwhich has improved veneer lamination and is economical to manufacture.

It is another object of the invention to provide glued laminated woodwhich, when its length and width are given, can be made from veneerswhose lengths and/or widths are smaller than those of the laminated woodproduct to be made.

It is another object of the invention to provide glued laminated woodwhich can be made longer without being influenced by the given lengthand/or width of the veneers therefor.

It is still another object of the invention to provide glued laminatedwood which can be made in many sizes or dimensions from veneers whosenumber of sizes or dimensions is reduced.

It is still another object of the invention to provide glued laminatedwood which can be made in various forms of veneer lamination.

It is still another object of the invention to provide glued laminatedwood which, after forming, is acceptable in appearance and can be usedwithout further processing.

It is another important object of the present invention to provide amethod of manufacturing the glued laminated wood product contemplated bythe invention.

It is still another object of the invention to provide a continuousmethod of gluing and laying-up of veneers in making of the gluedlaminated wood product which has distinct labor saving advantages.

BRIEF DESCRIPTION OF THE INVENTION

The foregoing objects are attained by providing a continuous run oflaid-up veneers which is made from a series of unit-length veneer sheetshaving the same length and laminated in a laid-up arrangement in whicheach veneer sheet is lapped on another and offset therefrom in thedirection of its length at a regular interval determined by the numberof plies to be in the laminated wood product and the length of the unitveneer sheets. The layers of veneers thus arranged are tacked, and gluedlaminated wood panels of one or more desired sizes are produced bycutting such a continuous length of laid-up veneers into the desiredlengths and then pressing the cut lengths to make the exposed surfacesof the veneer sheets flush with each other. Alternatively, dependingupon the arrangement and the type of hot press for forming the gluedlaminated wood, an indefinite and substantially continuous length ofglued laminated wood, from which panels of the desired lengths may becut, can be produced.

The glued laminated wood, including thus produced has a novel structurein that each veneer sheet therein has tandemly spaced straight lengthportions which are parallel to each other, but successively displacedfrom each other in the direction of the thickness of the laminated woodproduct, there being a somewhat S-shaped curved length portion of theveneer sheet between any successive pair of these straight lengthportions. The extent of the referred to displacement of each successivestraight length portion is equal to the thickness of the adjacent veneersheet, and the number of such straight length portions in each veneersheet is equal to the number of plies or veneer laminations in thelaminated wood product being made. The length of each such straightlength portion is nominally determined by dividing the length of theunit veneer sheet (measured in the direction of formation of thelaminated wood) by the number of plies. Thus, the endmost straightlength portions of each veneer sheet will respectively appear on theopposite faces of the laminated wood product and form a portion of suchfaces.

The unit-length veneer sheets are substantially flat when the necessaryglue is applied to their overlapping length portions and they are laidup in the aforementioned successively lapped relation. It is apparentthat all of the veneer sheets will be inclined to the horizontal andwill extend across the thickness of the laid-up arrangement thereof.Preferably, the unit-length veneer sheets are laid up substantially in acontinuous manner, which is followed by a tacking operation fortemporarily laminating the glued plies of veneer sheets together. Aftertacking, panels of laminated veneer sheets of any selected sizes are cutfrom the continuous lamination of veneer sheets, and the individualpanels are then hot-pressed to cause permanent formation of theaforementioned straight length and curved length portions in eachlaminated veneer sheet to produce a flattened thickness in the gluedlaminated wood panels and also for curing the lamination glue, therebyto fix the shapes of the veneers therein.

In its preferred embodiment, the invention further contemplates acontinuous manner of application of glue to each veneer sheet, before itis laid up, by which those areas on the sheets which will appear on thefaces of the glued laminated wood are automatically shielded from theglue application, yet the glue is applied to all of the areas on whichit is intended. This is accomplished by arranging a single row of theveneer sheets in lapped relation on a flight conveyor, preferablylocated above the main laying-up conveyor and which travels in theopposite direction, and applying the glue by a glue spreader along onlythe top surfaces of the lapped sheets. The unit veneer sheets with theglue thus applied are then successively dropped onto the main conveyorin their intended laid-up arrangement, as will be seen.

After the glued laminated wood panels have been formed, filler materialmay be applied to fill in the naturally occurring grooves adjacent theends of the veneer sheets to smooth one or both faces of the panel.Alternatively, a conventional panel-sized veneer sheet overlay may belaminated onto one or both faces, whereupon the panels will have theappearance of conventional panels. Still another alternative would be toavoid the formation of such grooves by beveling one or both ends of eachveneer sheet before forming the laminated wood, as will be seen.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

These and other objects, features and advantages of the invention willbecome apparent to those skilled in the art from the followingdescription of the basic structure of plywood and various embodiments ofglued laminated wood according to the present invention, and methods forits manufacture, which description is made with reference to theaccompanying drawings, wherein:

FIG. 1 is a fragmentary perspective view illustrating the basiclaminated structure of veneers as it appears in glued laminated woodaccording to the invention;

FIG. 2 is similar to FIG. 1, illustrating the same basic laminatedstructure of veneers in the glued laminated wood of the invention, butwherein the veneers have beveled ends for providing uninterruptedsurfaces on the plywood;

FIG. 3 is a fragmentary side view of glued laminated wood of theinvention, showing a manner of veneer lamination which is slightlydifferent from that of FIG. 1;

FIGS. 4 to 7 are fragmentary side views showing other possible end formsof each veneer and laid-up arrangements of such veneers;

FIG. 8 is a partial perspective view showing a typical unit veneer sheetwhich is used as a component veneer for fabricating glued laminated woodpanels in accordance with the invention;

FIG. 9 is a partial perspective view showing a parallel laminated woodpanel according to the invention produced using unit veneer sheets asillustrated in FIG. 8;

FIG. 10 is similar to FIG. 9, but showing another embodiment of aparallel laminated wood panel produced using unit veneer sheets havingbeveled ends;

FIG. 11 is a partial perspective view showing annother unit veneer sheetwhich is used as a component veneer for making glued laminated woodpanels;

FIG. 12 is a partial perspective view showing the embodiment of aparallel laminated wood panel produced using unit veneer sheets asillustrated in FIG. 11;

FIG. 13 is similar to FIG. 12, but showing another embodiment of aparallel laminated wood panel produced using unit veneer sheets similarto that of FIG. 11, but having beveled ends;

FIG. 14 is a fragmentary perspective view of a unit veneer sheet whichis made using two veneer sheets jointed together;

FIG. 15 is a partial perspective view of the embodiment of a plywoodpanel of the invention produced using the unit veneer sheets asillustrated in FIG. 14;

FIG. 16 is similar to FIG. 15, but showing another embodiment of a gluedlaminated wood panel produced using unit veneer sheets similar to thatof FIG. 14, but having beveled ends;

FIG. 17 is a partial perspective view of a unit veneer sheet which ismade using three pieces of veneers jointed together;

FIG. 18 is a partial perspective view showing the embodiment of a gluedlaminated wood panel of the invention produced using unit veneer sheetsas illustrated in FIG. 17;

FIG. 19 is similar to FIG. 18, but showing another embodiment of a gluedlaminated wood panel produced using unit veneer sheets similar to thatof FIG. 17, but having beveled ends;

FIG. 20 is a partial perspective view showing another unit veneer sheetwhich is made using three pieces of veneers jointed together;

FIG. 21 is a partial perspective view showing the embodiment of a gluedlaminated wood panel of the invention produced using a plurality of theunit veneer sheets shown in FIG. 20;

FIG. 22 is similar to FIG. 21, but showing another embodiment of a gluedlaminated wood panel of the invention produced using unit veneer sheetssimilar to that shown in FIG. 20, but having beveled ends;

FIG. 23 (A) and (B) are partial perspective views showing respective,alternate grain arrangements in unit veneer sheets made of two pieces ofundersized veneers jointed together;

FIG. 24 is a partial perspective view of the embodiment of a plywoodpanel of the invention produced by laying up alternate unit veneersheets as shown in FIGS. 23 (A) and (B);

FIG. 25 is similar to FIG. 24, but showing another embodiment of a gluedlaminated wood panel produced in the same manner as that of FIG. 24, butwherein the unit veneer sheets have beveled ends;

FIG. 26 is a schematic illustration of preferred method of manufacturingthe aforesaid embodiments of glued laminated wood panels, includingplywood panels, according to the invention;

FIG. 27 is an enlarged sectional view of veneers, showing possiblevariations in the relative lapped positions of one veneer sheet onanother during the laying-up step in the glued laminated woodmanufacturing method illustrated in FIG. 26;

FIG. 28 is a similarly enlarged sectional view of veneers, showingpossible variations in the relative lapped positions of one veneer sheeton another during the gluing step in the glued laminated woodmanufacturing method illustrated in FIG. 26;

FIGS. 29 and 30 are partial perspective views, respectively, showingalternative types of flight conveyors which may be used to convey theunit veneer sheets during the gluing and laying-up steps inmanufacturing the glued laminated wood panels according to the methodillustrated in FIG. 26;

FIG. 31 is a schematic diagram illustrating the operative relationshipsbetween the conveyor drives used in the gluing and laying-up processes;

FIG. 32 is a fragmentary perspective view of glued laminated wood inaccordance with the invention having overlay sheets adhered to itsrespective faces; and

FIG. 33 is a diagramatic illustration of the manner of cutting unitveneer sheets from random length logs, for use in practicing the presentinvention.

Referring first to FIG. 33, there is illustrated a conventional mannerof producing a continuous length of veneer sheet V from a log 40 byforced rotation of the log in the direction of arrow X, against theknife blade Y, causing the veneer V, having a thickness t, to peel offin the direction of arrow Z. The wood grain G extends in the directionof the length of the log 40, as is well understood.

When making a conventional glued laminated wood panel (not shown), thelength of the panel is limited to the length of the log 40; e.g., a4'×8' plywood panel calls for a log whose length is at least 8', whichmeans that a veneer lathe which is capable of handling at least 8' longlogs has previously been necessary for making such 4'×8' panels.According to the present invention, however, any sized panels can beproduced from a plurality of unit veneer sheets, such as the unit veneersheet 3 shown in FIG. 8 whose length is indicated by L1 and its width W.The width of the panel to be made is determined by cutting the veneer V(FIG. 33) peeled from the log 40, into a width W, in this case 4'. Onthe other hand, since the series of unit veneer sheets 3 are laid up andlaminated successively in the direction L1 (FIGS. 8 and 33), the gluedlaminated wood panel can be made as long as any required dimension, say8'. In this way, the 4'×8' panel can be produced from a log 40 whoselength does not have to be at least 8' long, but may be much smallerthan that, say only 3' long.

Turning now to FIGS. 1 and 2, the basic laminated structure of veneersglued together to form glued laminated wood according to the presentinvention is illustrated wherein the glued laminated wood, though it isshown only in a partial view, is designated by reference numeral 1, andveneers constituting the layers or plies of such glued laminated wood 1are indicated by reference numeral 2. For clarity of understanding, nowood grain pattern is shown on the laminated wood product in FIGS. 1 and2.

The present invention contemplates the production of glued laminatedwood, having any desired finite length, which may be obtained from apotentially continuous length of laminated wood formed by a series ofrelatively small-sized unit-length veneer sheets laminated in a regularmanner so as to form such continuous length of glued laminated wood. Forconvenience in describing the structure of glued laminated woodaccording to the present invention, the veneer lamination structure ofthe product will be explained herein on the assumption that the gluedlaminated wood which is partially shown in FIGS. 1 and 2 (and also inother similar drawings illustrating individual different embodiments)constitutes a fragmentary showing of either the finished, cut laminatedwood panel or the glued laminated wood as formed in a continuouslyextending length from which the plywood panels may be cut, because theshapes of the veneer laminations are the same in both.

Referring to FIG. 1, the glued laminated wood in accordance with theinvention is formed by laminating a series of unit veneer sheets 2, eachhaving the same thickness t and the same length L. In the illustratedembodiment, they are built up into a five-ply or five-layerconfiguration, as most clearly seen at the cut-away end section of theillustrated glued laminated wood 1. In making the glued laminated wood,a series of such unit veneer sheets 2 are laminated together in alaid-up arrangement so that each of the veneer sheets 2 is partlysuperimposed, or lapped, on another veneer sheet 2 positioned in anadjacent layer, the upper sheet being offset from the other, i.e.,having its one end spaced from the correspondingly adjacent end of theunderlying sheet, at a length interval l. Thus, the successively laid-upunit veneer sheets 2 may form an indefinite, continuous length. Whensuch a laid-up arrangement of veneer sheets 2 is pressed flat, eachveneer sheet is deformed, and displaced, or stepped in the direction ofthe thickness T of the laminated wood, at the same regular intervals l,at the locations corresponding to the ends of the successive veneersheets. As will be seen, each successive veneer sheet is offset fromeach other at the same interval l, and it will be noted that eachcomponent veneer sheet 2 thus deformed includes respective straightlength portions 1a forming portions of the opposite faces of thelaminated wood product, and straight length portions 1b extendingparallel thereto in tandem relation and successively displaced from eachother in the direction of the thickness T of the product. Between eachpair of straight length portions a generally S-shaped, curved lengthportion 1c is formed commensurately. A finished glued laminated woodpanel having any desired length may be obtained by cutting suchsubstantially continuous length of the laminated wood.

In the continuously extending glued laminated wood having a preselectednumber N of veneer plies and composed of veneer sheets 2 each having alongitudinal dimension L which are offset at length intervals l, therelationships between N, L and l may be formulated such that L issubstantially equal to the product of N and l, i.e., L=Nl. The lappingdistance or lapped length portion of each veneer sheet 2 is thereforeexpressed as L - L/N. In order to ensure consistency in the number ofveneer plies in the glued laminated wood 1 for attaining substantialuniformity in the product thickness throughout its length, the componentveneer sheets 2 should be offset when lapped on each other at suchregular intervals that the leading end 2a of any veneer sheet 2 on oneface of the the product and the trailing end 2b of a veneer sheet 2exposed on the other face thereof are positioned in oppositely alignedrelation to each other across the thickness T of the product, asexemplified in FIG. 1. Therefore, consistency in the number of veneerplies in the laminated wood 1 is assured by predetermining the value forl correctly with relation to the desired number N of veneer plies andthe length L of each component veneer sheet 2 or, alternatively, bypredetermining the value for L with relation to N and l. As a concreteexample, when glued laminated wood of five-ply configuration (N=5) is tobe made from veneer sheets each having a length of 300 mm (L=300), theoffsetting length interval l will be about 60 mm (or 300/5). It will nowbe apparent to those skilled in the art, to increase the number ofveneer plies in the glued laminated wood 1, the value for L is increasedand/or the value for l is decreased accordingly; and that, to decreasethe number of plies, the reverse is true.

In the glued laminated wood of FIG. 1 which is composed of veneer sheets2 whose ends are square-cut, recessed portions R will inevitably beformed extending across the width of the product on both faces 1d, 1ethereof at locations which are spaced at intervals corresponding to thelengths l. Such recesses may be left as they are without any additionalprocessing if so desired, e.g. for any particular appearance effect,although they may be easily eliminated by applying filler materialtherein. Alternatively, additional grooves may be formed so as tocamouflage the original recesses.

Referring now to FIG. 2, the glued laminated wood 1 is fabricatedsubstantially in the same manner as the glued laminated wood of FIG. 1,but the component unit veneer sheets 2 for its laminated constructionare provided at their ends 2a, 2b with bevels formed by scarf-cutting orany other convenient process. The result is that the glued laminatedwood 1 made from such beveled veneer sheets will have complete flatnesswithout the referred to recesses R (FIG. 1) on both faces thereof. Whenveneer sheets 2 having such beveled ends are used for lamination,however, it is important that each sheet 2 be accurately overlapped sothat the beveled faces of each pair of opposed ends 2a, 2b on theopposite faces of the product overlap each other with reference to theirsectional alignment, as shown in FIG. 2, to achieve complete flatnesswithout either recesses or projections on the product faces. In such acase, if the length L of each component veneer sheet 2 for the gluedlaminated wood of FIG. 2 is the same as that of FIG. 1, the length l ofthe veneer offset intervals should be slightly smaller in FIG. 2 than inthe case of FIG. 1, because the members of each pair of opposing beveledends 2a, 2b extend beyond each other for a slight distance, as will beunderstood.

It should be noted here in connection with the aforementioned relationof l=L/N that in the glued laminated wood of FIG. 1, each pair of theadjacently opposite ends 2a, 2b are preferably positioned with somelongitudinal spacing being provided in the sectional alignment betweenthe extreme ends thereof, whereas in the glued laminated wood of FIG. 2each pair of the adjacently opposite beveled ends 2a, 2b is in fullyoverlapping relation to each other. Thus, the value for l varies fromcase to case even if the values for L and N remain the same. Inaddition, although the length L designates the longitudinal dimension ofeach component veneer sheet 2 in a straightened state, the actual valuefor L as mesured in the longitudinal direction of the formed laminatedwood will be slightly smaller. Though there actually exists a slightdeviation from the relationship l=L/N, it will be understood, having thefeatures of the laminated wood structure of the invention in mind, thatsuch deviation is considered to fall within the scope of the formulationl=L/N.

Reference is now made to FIGS. 3 to 7 showing various examples of theshapes of the veneer ends, and relative alignment relationships of theoppositely disposed respective ends 2a, 2b on opposite faces of thelaminated wood.

Referring to FIG. 3 which shows in side elevation a portion of gluedlaminated wood 1 having five plies of veneer sheets 2 laminatedtogether, each veneer sheet 2 has squarecut ends and is lapped onanother using an offset interval such that the opposed ends 2a, 2bextend beyond each other for a slight distance, with the result thatoutwardly projecting portions are formed on both faces of the laminatedwood. Of course, when the laid-up veneer sheets are pressed to deformthe laminations, the faces of the press accommodate these projections,as will be understood. These projections on the laminated wood may beleft as they are if so desired, but may be removed readily by sanding orcutting, as indicated by phantom lines, for producing substantially flatsurfaces on the product faces.

FIGS. 4 to 7 show six plies of veneer sheets 2, respectively, which arejust laid-up and are yet to be glued together to form the completelaminated wood product. In FIG. 4, each veneer sheet 2 has beveled endswith their beveled faces facing inwardly. The ends 2a, 2b are positionedin overlapping relation as illustrated, so that their beveled facesextend beyond and face each other. Glued laminated wood obtained bypressing these six plies of veneer sheets 2 to cause the aforementioneddeformation thereof is similar to the glued laminated wood of FIG. 2,though the latter is only of five-ply structure. FIG. 5 shows six pliesof veneer sheets 2 each of which has beveled ends whose beveled faces,unlike the counterparts of FIG. 4, face outwardly. Glued laminated woodresulting from such layers of veneer sheets 2 after pressing is similarto the glued laminated wood of FIG. 3 after removal of the excessmaterial from the ends as previously described. In FIG. 6, one end ofeach veneer sheet 2 is beveled while the other end thereof issquare-cut, and each such veneer sheet is placed so that the ends 2a, 2bare substantially in vertical alignment with each other at their extremeends. Accordingly, after the veneer sheets 2 are deformed for laminatingthem into the glued laminated wood product, one face thereof will beformed flat while the other face will be formed with recessed portionstherein. In FIG. 7, each component veneer sheet 2 has ends 2a, 2b whichare chamfered or rounded, and which are spaced longitudinally apart onthe opposite faces of the product, with reference to an imaginary line(not shown) extending perpendicular to its thickness. The resultingglued laminated wood will have recesses on both faces thereof, and theexposed edges of each veneer sheet 2 will be rounded, accordingly.

Further embodiments of the glued laminated wood of the invention willnow be described with reference to FIGS. 8-25.

FIG. 8 shows a unit veneer sheet 3 having a longitudinal dimension L1 inthe direction of its wood grain G. A series of such unit veneer sheets 3are laminated together in the above-described manner for building upglued laminated wood, from which laminated wood panel 4 of theembodiment shown in FIG. 9, having a five-ply configuration, may beobtained.

In the embodiment of glued parallel laminated wood 4 shown in FIG. 9, itis fabricated by parallel-laminating a series of the unit veneer sheets3 of FIG. 8, with all of their grains G extending in the longitudinaldirection of the laminated wood to be made. Therefore, each unit veneersheet 3 will be offset in the direction of its wood grain from eachadjacent veneer at an interval of predetermined length l1, so as to forma continuous length of parallel laminated wood. A panel 4 of any desiredlength may be cut from such continuous length of glued parallellaminated wood.

The faces of glued parallel laminated wood 4 inevitably have recesses Rformed therein adjacent to the ends of each veneer sheet 3, but thesemay be eliminated by applying any suitable filler material therein. Ifdesired for any reason, such recesses may be retained as they are,without any further additional processing, or additional grooving may beprovided so as to camouflage the recesses. Though the veneer sheet 3 inFIG. 8 is shown as a solid sheet, it may contain therein one or morejoints 3a at which two pieces of undersized veneer sheets areend-jointed to make a full-sized unit veneer sheet having the length L1,e.g. when it is desired to use veneers which are shorter than L1. Suchjoints may be formed easily by using any known method such asbutt-jointing, scarf-jointing, or any other convenient jointing.

Another embodiment of the the laminated wood 4 as shown in FIG. 10 issimilar to that of FIG. 9, but differs therefrom in that the laminatedwood is composed of veneer sheets 3 whose ends are beveled in theinwardly facing direction, thus corresponding to FIG. 2. This embodimentis advantageous as compared with its counterpart in FIG. 9, whencontinuity in surface flatness is a major concern in product quality.

Reference is now made to FIG. 11, wherein a unit veneer sheet 5, havingthe dimension L2 across its wood grain G is shown. A series of such unitveneer sheets 5 are used to fabricate a substantially continuous run ofthe laminated wood from which laminated wood 6 of any required length asshown in FIG. 12 may be cut.

In the embodiment of FIG. 12, the parallel laminated wood 6 is made bylaminating a series of the unit veneer sheets 5 of FIG. 11 in parallelrelation to each other with all of their grains G extending across thelongitudinal direction of the product. Accordingly, each unit veneersheet 5 will be offset, in the direction across the wood grain thereof,from each adjacent veneer sheet at a predetermined length interval l2for forming a continuous length of glued parallel laminated wood. Thelaminated wood 6 of any desired length may be obtained from suchcontinuous length of parallel laminated wood.

FIG. 13 illustrates another embodiment of the glued parallel laminatedwood 6, which is made using a series of laminated unit veneer sheets 5,having beveled ends as in previous embodiments for preventing recessesfrom being produced on the product faces.

Referring to FIG. 14, a unit veneer sheet 7 is shown which, unlike thesolid unit veneer sheets shown in FIGS. 8 and 11, includes two pieces ofundersized veneers 8 and 9 which are jointed together along their lineof abutment 7a to make the full-sized unit veneer sheet 7 having alongitudinal dimension L3. The undersized veneer 8 on the left-hand sideas shown has its grain G1 oriented in the longitudinal direction of thelaminated wood to be made; while the other undersized veneer 9 has itsgrain G2 thereacross. When making a unit veneer sheet 7 which includestwo jointed pieces of undersized veneers 8 and 9, the dimension of theveneer 8 in the direction of its grain G1 and the dimension of theveneer 9 across its grain G2 should preferably be such that either ofthe dimensions is greater than the interval lengths l3 (FIGS. 15 and 16)at which the unit veneer sheets 7 will be offset successively from eachother in the lamination thereof for making of the product. By so doing,the abutment line 7a may be prevented from appearing on the laminatedwood product faces. Furthermore, to maintain the strength of theresulting laminated wood the dimension of the veneer 8 having its grainG1 along the length L3 should preferably be the sum of said intervallength l3 and a dimension which is greater than five times, or morepreferably in the range of from 15 to 150 times, the thickness of theveneer sheet 7 so that the jointing line 7a may not be positionedclosely enough to the adjacent lapping end of its overlying veneer sheetto affect the strength of the laminated wood at such jointing line, aswill be understood by those skilled in the art.

When a series of overlapped veneer sheets 7 having therein a side-to-endjoint are glued together to form a laminated structure according to theinvention, glued laminated wood 10 as shown in FIG. 15 will result. Thatis, in the illustrated case of a five-ply lamination, the upper two orthree plies thereof have their grains G1 extending in the longitudinaldirection of the glued laminated wood 10, while the lower two or threeplies have their grains G2 set thereacross.

The embodiment of plywood shown in FIG. 16 differs from that of FIG. 15in that the glued laminated wood is made of similar unit veneer sheets7, but each having its ends beveled in the inward direction, each unitvenneer sheet being offset from another at a sightly smaller interval,as previously explained.

FIG. 17 shows still another form of a component unit veneer sheet 11which is integrally formed by jointing three sections of undersizedveneers 12, 13 and 14, along their respective lines of abutment 11a, 11binto a unit veneer sheet 11 having a longitudinal dimension L4. In thisunit veneer sheet 11, its respective end sections 12 and 14 have theirwood grains G1 extending in the direction of the length L4, whereas theveneer section 13 at the center has its grain G2 extending thereacross.Each of the dimensions of the undersized veneers 12 and 14 in thedirection of their grains G2 is made greater than the interval lengthsl4 (FIGS. 18 and 19) at which the unit veneer sheets 11 will be offsetfrom each other when laminated to make the glued laminated wood product.Furthermore, the dimensions of said veneers 12 and 14 should preferablybe the sum of said interval length l4 and a dimension which is greaterthan five times, or more preferably in the range of from 5 to 150 times,the thickness of the veneer sheet 11, for the same reasons statedpreviously in connection with FIG. 14.

Laminating a series of such integrally formed unit veneer sheets 11 ofFIG. 17 into a five-ply structure according to the invention willeventually produce glued laminated wood 15 as illustrated in FIG. 18. Inthis embodiment, a cross-banded structure which is similar to athree-ply configuration can be created, as seen clearly at the sidesection thereof. That is, in the case of the illustrated five-plylamination, one or two plies of the veneer sheets 11 at the top and atthe bottom of the glued laminated wood 15 have their grains G1 extendingin the direction of the length thereof, and two or three plies at thecore portion of the laminated wood have their grains G2 runningthereacross.

The embodiment of the glued laminated wood 15 in FIG. 19 differs fromits counterpart shown in FIG. 18 in that each component unit veneersheets 11 therefor has beveled ends, and is offset from each of itsadjacent veneer at a slightly smaller interval which corresponds withthe beveling as previously explained.

In FIG. 20, a unit veneer sheet 16 is shown which has three sections ofundersized veneers 17, 18 and 19 jointed together, along respectiveabutment lines 16a, 16b, into the length L5 of a full-sized unit veneersheet 16. This veneer sheet 16 is similar to that shown in FIG. 17, butdiffers therefrom in that the undersized veneer 18 at its center has itsgrain G1 extending in the direction of the length L5, whereas the veneersections 17 and 19 at the ends have their grains G2 extending thereacross. Like the veneer sections 12 and 14 (FIG. 17), the undersizedveneers 17 and 19, as measured along the length L5 or across the grainsG2 thereof, have dimensions greater than the length l5 (FIGS. 21 and 22)of the intervals at which the unit veneer sheets 16 will be offset fromeach other in the lamination thereof into a continuous length of gluedlaminated wood for the same reason stated in connection with FIG. 14.

The glued laminated wood 20 which results from laminating suchintegrated unit veneer sheets 16 according to the invention is shown inFIG. 21. Its cross-banded structure is arranged in a manner similar tothat of the embodiment of FIG. 18, although each veneer layer isreversed in respect of the direction of its wood grains.

FIG. 22 illustrates another embodiment of the glued laminated wood 20,wherein the faces thereof are formed flat, with no recesses such asthose seen in FIG. 21, by providing inwardly beveled ends on eachcomponent unit veneer sheet 16, and laminating the veneer sheets withtheir beveled ends overlapping and confronting one another, aspreviously explained.

Reference is now made to FIG. 23 which shows two unit veneer sheets 21and 24, each having two sections of undersized veneers 22, 23, and 25,26 respectively, which are jointed together at the lines of abutment21a, 24a into unit veneer sheets having the length L6, respectively. Inthe unit veneer sheet 21, its undersized veneer 22 has its grain G1extending in the direction of the length L6, and the other veneer 23 hasits grain G2 extending thereacross. With reference to the unit veneersheet 24, its undersized veneer 25 has its grain G2 extending across thelength L6 and the other veneer 26 has its grain G1 therealong. Thedimensions of the respective undersized veneers 22, 23, 25 and 26 asmeasured along the length L6 are preferably made greater than the lengthl6 (FIGS. 24 and 25) of the intervals at which the unit veneer sheets 21and 24 will be offset from one another in the lamination thereof whenmaking a continuous length of glued laminated wood so that the abutmentlines 21a and 24a may not appear on the faces of the resulting product.As to the veneer sections 22 and 26 having their grains G1 extendingalong the length L6, the dimensions thereof along the length L6 shouldpreferably be the sum of said interval length l6 and a dimension whichis greater than five times, or more preferably in the range of from 15to 150 times, the thickness of the veneer sheets 21, 24, to avoid adecrease in strength of the resulting product due to the abutment lines21a and 24a being formed close to the adjacent lapping ends of thesuccessive overlying unit veneer sheets in the laminated wood structure.In the illustration of FIG. 23, the two unit veneer sheets 21 and 24 aremade substantially symmetrical with respect to the jointing lines 21aand 24a, respectively.

The glued laminated wood 27 which is made from the combination of theabove two kinds of unit veneer sheets 21 and 24 is exemplified in FIG.24. In this particular embodiment, the unit veneer sheets are arrangedand laid up in the ratio of two of the veneer sheets 21 to one of theveneer sheets 24, whereby glued laminated wood having a compositecross-banded structure is created, as seen at the side section thereofin FIG. 24. Though not shown in the drawings, various embodiments oflaminated wood having the unit veneer sheets arranged in ratios otherthan the above two-to-one, e.g. one veneer sheet 21 to any desirednumber of veneer sheets 24, three veneer sheets 21 to any desired numberof veneer sheets 24, and so forth, may be contemplated.

FIG. 25 exemplifies another embodiment which is similar to that of FIG.24, but whose component unit veneers have inwardly beveled ends, asshown.

As will now be apparent, the present invention can be utilized in makingvarious types of glued laminated wood, including laminated wood havingparallel laminated veneers as well as cross-banded structure, dependingupon the orientation of the wood grains of the component veneers and theselected combination of undersized veneers used in making the componentunit veneer sheets. since each type of laminated wood has its ownapplications it will be apparent that each of the previously describedembodiments has a particular use.

It would be preferable that the veneer sheets be used in the making ofglued laminated wood according to the invention have a thickness in therange of from 1 to 4 mm. Since the stepped deformation of each veneersheet which occurs during the process makes use of its inherentflexibility, the greater the thickness of the veneer sheets, the moredifficult it will be to successfully make the product. With this and theabove range of preferred thicknesses of veneer sheets taken intoconsideration, the practical range of thicknesses of the resultingproduct will be from about 6 to 50 mm. Depending upon the veneerthickness and other factors, the present invention will exhibit aremarkable advantage in terms of economy when the component unit veneersheets hve dimensions of from 100 to 1,000 mm in the L direction. As tothe number of plies in the laminated wood, any desired number can beselected, preferably from within the range of from 3 to 12 pliesaccording to various factors including the desired thickness of productto be made, the veneer thickness to be used, the particular wood speciesof which the veneer is made, and so on.

The method of manufacturing glued laminated wood, including according tothe present invention will now be explained with reference to FIGS. 26to 31:

FIG. 26 shows a schematic diagram illustrating the basic proceduralsteps for manufacturing the continuously produced product, which includea gluing (adhesive applying) process or station designated generally byreference letter A, followed sequentially by a laying-up process orstation B, a tacking station C, a cutting station D, and a final bondingstation E.

In the gluing station A, a series of unit veneer sheets 2 each havingthe same length L and thickness are arranged with their respectiveleading ends lapped on the trailing ends of the preceding veneer sheetsas shown in the drawing. In such arrangement, they are conveyed face-upby conveyor 28 in the direction of the arrow successively beneath a gluespreader 38, which coats the upper surfaces of the veneer sheets 2 witha continuous film of glue which covers only the exposed surfacesthereof, the glue being indicated by the dots GL in the drawing. Thecoating of glue may be accomplished by use of any suitable glue applyingapparatus such as the glue spreader 38 shown schematically in FIG. 26, acurtain coater, a film-glue applying device which is disclosed in theCanadian Patent Application No. 418,699 filed on Dec. 29, 1982 by MeinanMachinery Works, or any other conventional means. Anyway, the gluingprocess A is performed in such a way that no glue is applied to theopposite underside surface of each veneer sheet 2, or on the lappedupwardly facing portion at the trailing end of the veneer sheet. Thelength of overlap of each veneer sheet on the other is nominally equalto the quotient determined by dividing the unit veneer length L by thenumber N of plies to be in the laminated wood structure, i.e. the samelength as the length l of offset of the veneer sheets in the laying-upoperation which follows.

As thus coated with glue, the unit veneer sheets 2 are transferred tothe subsequent laying-up station B, by sequentially dropping the sheets2, as indicated by arrows F, from the conveyor 28. On the laying-upconveyor 28a, each veneer sheet 2 is lapped only on the glued portion ofits preceding sheet, thereby exposing only the unglued portions of theveneer sheets. That is, in the laying-up station B each veneer sheet 2,which in the illustrated laying-up station has reversed its direction ofmovement from that of the gluing conveyor 28, is laid on the precedingveneer with its now unglued leading end exposed as a result of thecontinuous or indexing movement of the preceding veneer sheet. It willtherefore be apparent that the lapped length portion, or glue coatedportion, on each veneer sheet is substantially equal to L-L/N.

As thus laid-up in a continuous, sequentially overlapped length, theseries of veneer sheets 2 are conveyed on conveyor 28a to the tackingstation C, which includes a cold press (not shown) or any otherconvenient device, such as a stapler, a hot-melt glue applicator, etc.,designed to temporarily hold the individual laid-up veneer sheets 2together in a laminated form while maintaining the correct relativepositions thereof.

The continuous lamination of veneers thus formed is transferred to thesubsequent cutting station D, where it is cut into the desired panellengths. The panels are then moved to the bonding station E whichincludes a device, such as a hot press, designed to cure the layers ofglue between the veneer sheets while pressing them to permanently setthem in their desired deformed shapes having the tandemly arranged anddisplaced straight length portions 1b and curved length portions 1c(FIG. 1). As will be noted from FIG. 1, during the bonding opeation atthe station E, each straight length portion 1b is displaced, in thedirection of the thickness T of the product, by a distance substantiallyequal to the thickness t of its adjacent veneer sheet. Of course, if theproduct is made of veneers having varying thicknesses, the extents towhich its straight length portions are displaced will be correspondinglyvaried. For example, in a typical hot press operation, pressure on theorder of about 7 to 21 kg/cm² (or about 3,000 to 9,000 lbs/ft²) isapplied at a temperature of about 120° to 176° C. to cure the gluebetween the veneers and permanently set and bond them together.

In the described method of manufacturing glued laminated wood, it isdesirable during the gluing process A that glue should be applied toeach veneer sheet 2 leaving an appropriate unglued portion to allow verylittle of the glue to be exposed when it is laid up on the precedingveneer sheet in the subsequent laying-up process B. For example, in anarrangement of veneer sheets 2 in the laying-up process B wherein eachpair of adjacently opposite ends 2a, 2b of two overlapped veneer sheets2 have their ends in vertical alignment with each other as exemplifiedby full lines in the fragmenting side elevational showing of FIG. 27,each veneer sheet 2 will have an exposed portion of its surface oneither face which is exactly equal to the distance of L/N (wherein Lrepresents the longitudinal dimension of each unit veneer sheet 2; and Nthe number of veneer plies in the laminated wood to be made). As statedearlier, in connection with the description of the product itself, theabove-said distance, and therefore the surfce area to be exposed, variesdepending upon the shapes of the veneer ends, the sizes thereof, therelative positions of each pair of the adjacently opposite ends 2a, 2b,etc. For example, when the edges of each pair of corresponding veneersheet ends 2a and 2b are arranged or laid up in other ways such that oneend overlaps the other a distance S, or such that the ends 2a, 2b arenot in transverse alignment, but are spaced apart from each other in thelongitudinal direction a distance S', as indicated by phantom lines inFIG. 27 respectively, the unglued area to be exposed should be decreasedin the case of the overlapping relation S, and increased when they areto be spaced apart as shown by S', respectively. In either event, it isdesirable that each veneer sheet 2 have glue applied at station A in away such as to maintain the appropriate unglued areas which will beexposed at the laying-up station B (FIG. 26).

Although maintenance of such unglued portion on each veneer sheet 2 maybe accomplished by properly controlling the glue applying device 38, itis more convenient to apply glue in a continuous manner to the series ofveneer sheets 2 which are successively lapped at their ends using theappropriate lapping distane, thus permitting the use of any known typeof glue applying device. The length over which the respective ends ofadjacent veneer sheets 2 are lapped on the gluing conveyor 28 (FIG. 26)and as will provide the unglued areas is determined by the lengthwisedimension of the surface area to be exposed in the laying-up process B(FIG. 26), which is the length interval l at which the veneers arelaminated in offset relation to each other. When the paired ends 2a, 2bof the upper and lower veneer sheets 2 in the laying-up process B arethemselves to be longitudinally overlapped as indicated by S, or aregoing to be longitudinally spaced apart from each other as at S' in FIG.27, the lengths over which the ends of any two adjacent veneer sheets 2are lapped in the gluing process A will be decreased or increased,accordingly, as indicated by phantom lines in FIG. 28. Regarding thevalue of S or S', depending upon the usage of the glued laminated woodeach is preferably within the range of less than 50 times or, morepreferably, less than 5 times, the thickness of the unit veneer sheet 2to be employed in making the product. Though it is ideal that the areaof unglued surface obtained in the gluing process A and the area ofsurface to be exposed in the subsequent laying-up process B shouldexactly coincide, errors are unavoidable in actual practice during boththe gluing and the laying-up processes A and B. To compensate for sucherrors, any practical adjustment may be made, as by increasing ordecreasing the areas of the unglued surfaces in the gluing station, etc.

FIGS. 29 and 30 respectively illustrate two types of flight conveyorswhich may be used to transport the veneer sheets 2 while retaining thecorrect overlapping relation between them during either the gluingprocess A or the laying-up process B (FIG. 26). The conveyor 28 shown inFIG. 29 includes several conveyor belts (only one of which is shown inthe drawing) having veneer sheet locating steps 29, for receiving thetrailing ends of the veneer sheets. The conveyor 30 in FIG. 30 includesseveral conveyor belts (only one of which is shown in the drawing)having veneer sheet locating pins 31 projecting therefrom, for the samepurpose. By placing each veneer sheet 2 onto the conveyors whether inautomatic, semiautomatic or manual manner, it will be transported whilebeing located and overlapped correctly in the longitudinal direction.Thus, a high standard of accuracy and stability in veneer positioningcan be achieved during the transporting of the veneer sheets througheither the gluing or the laying-up processes.

Referring now to FIG. 31, to permit the gluing and laying-up processesto be carried out in close conjunction with each other in order tosynchronize the relative positioning of the veneer sheets in the twoprocesses, a common drive 32 is provided for directly driving theconveyor 28 for the gluing station A and for driving the conveyor 28afor the laying-up station B via any suitable speed-reducing device 33,as shown schematically in FIG. 31. By such drive arrangement, the twodifferent processes A and B can be operatively synchronized so thaterror, if any, between the rates of travel of the veneer sheets duringthe two processes will take place at a given, and therefore,predictable, value. Therefore, adjustment for compensating the error maybe made with ease.

If the drive 32 operates in a continuous manner, a cold press of acontinuous type may be used in the tacking station C. If the drive 32 iscapable of automatically interrupted operation, it is possible to employa cold press having intermittent operation for the tacking process C.

When it is permissible for the glue coating on the veneer sheets 2 to beexposed in the subsequent laying-up process B, or when it is intended tohave such exposure of glue on the product, the gluing process A may beconducted without maintaining the above-mentioned specific unglued areason the veneer surfaces. For example, the veneer sheets 2 may be merelypassed through the glue spreader 38 (FIG. 26) one after another inend-to-end relationship, without lapping their ends as shown in FIG. 28,so as to coat the glue on the entire surface of each veneer sheet. By sodoing, a continuous length of glue exposure will appear on the face orfaces of the continuously laid-up veneer sheets 2 formed in thelaying-up station B. Such exposure of glue on the laid-up veneers ispermissible or even desired, depending upon the type of laminated woodpanel to be produced. For example, the glue which is exposed on the facecan facilitate the application of an additional layer of overlay of aflat sheet of veneer, printed paper, board or any other suitable overlaymaterial O which would be laminated onto the face or faces of theproduct, as illustrated in FIG. 32. The overlay sheet O may be addedduring or after the laying-up process, as desired.

Thus, it is to be understood that the particular embodiment of themethod of manufacturing glued laminated wood according to the invention,specifically with reference to the gluing process A, will vary dependingupon its intended relationship with the subsequent laying-up process B.Thus, the gluing method may be conducted in a variety of ways other thanthose described above.

With regards to the manner in which the gluing and laying-up stations Aand B are disposed relative to each other for transferring the veneersheets from the former to the latter, they may be located on the samelevel by arranging the gluing station A on the upstream side and thelaying-up station B on the downstream side with reference to thedirection of transfer of the veneer sheets 2, although they are locatedon different levels in the embodiment of FIG. 26. Furthermore, these twoporcesses A and B may be arranged in line with each other, wherein theconveyor 28a is moved in the same direction as the conveyor 28, withoutbeing reversed as in the illustrated embodiment of FIG. 26, and insteadeach veneer sheet 2 coated with glue in the gluing station A is turnedby reversing the leading and trailing ends thereof before it istransferred to the subequent laying-up station B to be lapped on theglued portion of its preceding sheet. Therefore, these two stations maybe operatively connected in any manner according to any specificrequirements.

Furthermore, in the method of laminated wood manufacturing shown in FIG.26, the tacking process C may be either replaced by, or immediatelyfollowed by the bonding process E by substituting or adding a hot pressof a type designed to operate in a continuous or intermittent manner,whereupon the laying-up process B and the final bonding process E can beintegrated into a wholly continuous process. In such an arrangement, thecontinuously produced glued laminated wood can be cut into any desiredlengths in the cutting process D which would then follow the bondingprocess E. Thus, any desired lengths of laminated wood panels can beproduced from a continuously produced run of glued laminated wood.

The present invention contemplates glued laminated wood having a novellaminated structure of veneers, which makes possible the formation oflaminated wood of any desired length from veneer sheets which are tooshort or too narrow for such desired length of the product, thuspermitting economical usage of veneer.

Regarding other general considerations associated with veneer orlaminated wood making such as the kind of wood to be used, thickness,size, how to to deal with lathe checks on the veneer surfaces, number ofplies, adhesives to be used, moisture content in veneers, etc., none areaffected in any way by the practice of the present invention, but aresubject to ordinary practices in glued laminated wood making.

While the invention has been illustrated and described with reference tovarious specific embodiments, it is to be understood that variousmodifications in the details of the glued laminated wood construction orits method of manufacture may be made without departing from the spiritand scope of the invention.

What is claimed is:
 1. Method of manufacturing glued laminated woodcomprising providing a plurality of unit veneer sheets, applying glue tosaid unit veneer sheets, laying up said unit veneer sheets insuccessively lapped relation in one direction of overlap, each of saidunit veneer sheets having substantially the same length in the directionof said laying-up, the successive length intervals of overlap of eachsaid unit veneer sheet on another in said direction of overlap eachbeing nominally equal to said unit veneer sheet length minus thequotient determined by dividing said unit veneer sheet length by thenumber of plies to be in said glued laminated wood, and pressing andcuring said laid-up veneer sheets to permanently deform and bond thesame and thereby establish the thickness of said glued laminated wood,each of said deformed unit veneer sheets having a plurality of straightlength portions and respective curved length portions between any twoadjacent ones of its said straight length portions, said straight lengthportions being in tandem parallel relation to each other andsuccessively displaced from each other in the direction of the thicknessof said glued laminated wood by a distance substantially equal to thethickness of the immediately adjacent, lapped veneer sheet.
 2. Methodaccording to claim 1, wherein each of said unit veneer sheets has equalthickness, and said length interval of overlap of each said unit veneersheet on another is varied from said nominal length interval by a lengthwhich is up to 50 times the thickness of one of said unit veneer sheets.3. Method according to claim 1, wherein said step of applying glue tosaid unit veneer sheets comprises arranging said unit veneer sheets insuccessively lapped relation in the direction of their said lengths, thelength interval of overlap of each said unit veneer sheet on another insaid arranging being nominally equal to said unit veneer sheet lengthdivided by the number of plies to be in said glued laminated wood,coating said glue substantially continuously along those overlappedsurfaces of said unit veneer sheets which face in one direction wherebysaid length interval on each unit veneer sheet is shielded from saidcoating of glue, and said subsequent step of laying up said unit veneersheets comprises substantially reversing the length interval of overlapof said unit veneer sheets whereby said glue coating glues therespective of said sheets one to another in successively overlappedrelation with said shielded length intervals on said sheets beingexposed.
 4. Method according to claim 3, wherein during said arrangingof said unit veneer sheets, said overlapped unit veneer sheets areconveyed in said arrangement by a first conveying means with saidglue-coated surfaces thereof facing upwardly, and said substantiallyreversing the length interval of overlap of said unit veneer sheetscomprises feeding said unit veneer sheets one at a time off from saidarrangement of said unit veneer sheets and laying up said unit veneersheets while conveying the same by a second conveying means.
 5. Methodaccording to claim 4, wherein said step of substantially reversing thelength interval of overlap comprises feeding said unit veneer sheets oneat a time off from the underside of said arrangement of unit veneersheets and dropping said unit veneer sheets on to said second conveyingmeans, said second conveying means being disposed below said firstconveying means, and conveying said sheets in direction which issubstantially opposite to that of said first conveying means.
 6. Methodaccording to claim 2, wherein said length interval of overlap of eachsaid unit veneer sheet on another is varied from said nominal lengthinterval by a length which is up to 5 times the thickness of one of saidunit veneer sheets.
 7. Method according to claim 1, wherein each saidunit veneer sheet comprises a solid sheet of veneer.
 8. Method accordingto claim 1, wherein each said unit veneer sheet comprises at least twoundersized sheets of veneer which are integrally jointed together toform said length of each said unit veneer sheet.
 9. Method according toclaim 8, wherein each said undersized sheet of veneer which is disposedat and forms an end of said unit veneer sheet has a length, as measuredin the direction of said laying-up, which is greater than a dimensiondetermined by dividing said unit veneer sheet length by the number ofplies to be in said glued laminated wood.
 10. Method according to claim8, wherein each said undersized veneer sheet which is disposed at andforms an end of said unit veneer sheet has a length, as measured in thedirection of said laying-up, which is greater than said dimension by anamount which is from about 5 to about 150 times the thickness of saidunit veneer sheet.